Scale



FJ. TROLL.

SCALE.

APPLICATION FILED AUG- 7. i919.

Patented Sept. 28, 1920.

2 SHEETS-SHEET 2.

:IIIIIIIIIIII- Hlllllllllllgas ' UNITED Asierras yPrirr-:ISJ'P o Price.

FREDERICK J. TROLL, OF BALTIMORE, MARYLAND, ASSIGNOR TQ THE LOADOMETEDYCOIMIIIEANI'Y:7 A C0R13ORA'JTIGN' DELAWARE.

SCALE.

specification of riettersratent. pafe'ntedisept. 28, 1920.

Application led August 7, 1919. Serial No. 315,834.

To all whom it may concern 4Be it known that I, FREDERICK J. TROLL, a aYcitizen of the `United States of America, residing in the city ofBaltimore, State of Maryland, have invented certain new and usefulImprovements in Scales, of which the following is a specification.

-In order to prevent destruction of road surfaces and foundations bymodern traffic, it has become necessary to limit .the pressure per unitof area that may be applied to the roads by vehicle tires, or, moreparticularly, to limit the weight consisting of load and vehicle perinch of tire width. Laws providing for this have been passed in variousStates, and such protection is essential wherever good roads are to bemaintained in the face of heavy trafiic. The adoption of such laws hasprobably been somewhat retarded on account of the diiiculties incidentto inspection. Where violation is merely vsuspected and can only besuspected until actually proved, to compel the driver' of a heavilyloaded vehicle to depart from his intended route in orderf that-thevehicle and load might'be weighed would work eX- treme hardship andinjustice.

The inventor seeks to 'overcome this difliculty by supplying aconvenient and de- ,pendable means for determining the bearing pressureon the tires 'at any time when and place where such a test may bedesired."

This apparatus may be used eitherby the operator of the vehicle to avoidviolation of the law or by the authorities, as traiic oflicers and thelike, to detect such violations, the same being convenientlytransportable, so that it may be carried by the traffic oiflcer,y in hismachine, and comparatively inexpensive, so that it may logically becomea part of the regular equipment as are the speedometer and 'othertesting and indicating devices, air gages, jacks, etc.

More particularly, the device consists in c the combination of a jack orlifting means by which a portion o f the vehicle may be lifted with aweight or pressure indicator.

In the preferred form of the invention I use a mechanical jack incombination with a `hydraulic `weighing device and a pressure indicatingmeans which may be calibrated to iead in terms ofthe weight lifted bythe Jac Determination of the weight on any wheel per unit of width ofthe tire may be'accomjack element of the ferringthe. load on i plishedin various ways by vuse of the weighing device of the invention. Theobvious method is to-lift one wheel by means of the combination, thustransthe wheel to the weighin g device. Under these circumstances itwill be obvious to those acquainted with the principles of mechanicsthat the weight indicated by the gage is 'not the exact weight whichrests on the tire. Ordinarily the wheel will be raised as in theregularn practice in changing tires, by placing the weighing deviceunder the axle just inside the wheel after themanner of operating anordinary Jack and the actual load on the tire must be calculated bymeasuring the moment arms of the downward pressure at the center of thevtire which is lifted and the upward supporting force at the weighingdevice, respectively, about the center of the opposite wheel on the sameaXle, and applying the usual formula to arrive at the unknown force, z'.e., the weight o-r downward pressure at the center ofthe tire of thewheel which has been lifted. This would,

however, raise fine questions as to the accuracy of measurements, etc.,affecting the accuracy of the result. Another practical method ofdetermining the"bearing pressure l or four weighing units may be used,all four wheels being supported at one time, each reading being dividedby the tire width to give the bearing pressure perY inch of tire width.The variation as to the individual wheels would of course depend on theplacing of the load. This may be used to give f the weight of the entirevehicle and its load,

which would be the same quantity determined if the vehicle were drivenon a scale like that used in weighing coal or ice, which is the onlycompeting apparatus now utilized in this connection.

In ,the accompanying drawing I have illustrated a weighingdeviceembodying the features of my linvention and various meth-^` odsof'applying the saine in the determination of the bearing pressure onthe tires of road vehicles.

'Tn the drawings Figure 1 is a v vertical central section of a weighingdevice constructed in accordance with my invention,

certain parts being shown in elevation. F ig. 2 is a plan of the same. rF ig. 3 is an elevation showing the rear axle of 'a truck looking fromthe back, with two of my weighing units in the process of determiningthe bearing pressure on the rear tires, both ends of the axle beingraisedy by the jacking element of the weighing device.

F ig. 4 is a'diagrammaticplanof a road vehicle to which four oftheweighing devices are applied. v

Fig. 5 is a similar diagrammatic view K showing the use of two weighingdevices in accordance with my invention.

. Fig. 6'is a detail elevation-of the gage.

- Referring to the drawings by numerals,` each of which is used toindicate the same or similar parts in the diferent figures, the weighingunit illustrated, particularly in Figs. 1 and 2, includes a base or 'pot1 in which is formed a Huid pressure or hydraulic cylinder2 coperating.with which is a piston 3. The cylinderhas its head or closed end 4 atthe bottom, and the piston has a piston rod or shank 5 working in asuitable guide orbearing 6 in the cap 7, and this shank 5 has a centralaxial threaded aperture 9 which coperates with and re, ceives thethreaded jack-screw shaft 10.v

Other features of the jack include a head 11 swiveled on the shaft 10, aknurled collar 12 secured tothe shaft, and a ratchet and4 'pawl element13 by which the shaft sure gage 17`connected to thev cylinder by- -lsuitable fittings 18. This gage will be more particularly described.

The base 1 is also provided with suitable handles 19 for manualengagement in placing, removing and packing the device. TheA piston hasleak preventing means or packing in the formL of a soft washer or diskl2O` which as shown. isof inverted cup shape having its edges 21 turnedso that they lie iat against the cylinder walls. This ,packling memberis held in position by a metal washer or disk\22 which as shown issimilarly formed, the same being in turn secured to the piston by asuitable meansas screws. 24. The cap 7 is secured to the cyllnderA orpot by means of cap screws 24 Ywhich pass through the cap andare'seatedA in the cylinderwall. Tlie rod-or shank 5 is held in a guideor bearing 6 in the cap .radial slot 27 therein and lheld by means ofscrews 28. p

,The knurled collar 12 is for use in turning the screw-shaftindependently of the ratchet, as in raising the screw to the positionvinwhich it engages the load. The ratchet mechanism 1'3 consists of aratchet gear 29 formed on the screw shaft. 'This gear, as shown, has aseries of notches or slots 30 to receive a sliding pawl or bolt 31. Thepawl is mounted to slide in a rotating or oscillating carrier 32 whichis apertured at 33 to receive the 7ratchet gear. The pawl 31 is carriedin a barrel or elongated opening 34 which opens into the aperture 33surrounding kthe sgear 29. The pawl isI shouldered at 35, and the barrel'34 is closed back of the shoulder by the insertionof a lever arm y36for actuating the pawl. This lever 'arm has a central longitudinalopening or bore 37 in alinement with the axis of the barrel 34, and inthis barrel, extending the length of the arm, is a control rod 38 havingat the rear end .a button 39 by means of which it maybe operated whendesired. The lever arm 36 is fastened iny the carrier by means of pinsor rivets 40 and the pawl is thrust forward against the lever arm 36 andagainst the shoulder 35 on the pawl, the pawl being in turn fastened tothe forward end of the rod 3'8 by a pin or rivet 43. .As shown, theV endof the r'od isinserted in an opening in the pawl and the shoulder 35 isin fact the rear sur- Lface of the pawl, the reduced ortion back of theshoulder being a part o the rod 38.

yThe pawl operates to turn the screw by engagement -with the ratchetnotches during .the forward. stroke of the arm, the back stroke beingNwithout effect on the position of the screw because theI pawl throws .itout of engagement. The bore or barrel 34 is made of circularcross-section, and to reverse the action of the lifting means, the pawlis withdrawn by a pull on the button 39 androtated by manual engagementof the same button to reverse position.

The construction of the gage 17 is shown in Fig. 6, though all thesedetails and the details of the jack are not considered material to theinvention. The type of gage illustrated is a hollow metal band or fiattube 50 bent in 'the form of an arc. One end of this tube is open andconnected to. the fittings 18 inside the gage box at 51. The other orfree end 52 is closed and conat 55 and .carrying a segment 56 on theopposite side of the pivot. This segment meshes with a small gear 57 onthe shaft of the indicating hand 58 moving over a calibrated face plate59. The gage may be calibrated in pounds pressure of the fluid in thecylinder, but is preferably calibrated in terms of pounds weightsupportedby the jack or lifting member. V

F'gs. 4 and 5 show diagrammatically the chassis of a road vehicle orrather the front wheels 60, rear wheels 61, rear axle 62, engine casting63, shaft 64. Tn Fig. 4 I have illustrated the application of four of myraising devices 65, two of them under the rear axle and two under thefront axle at convenient points of engagement adjacent each wheel. Whenthus applied the weight on each wheel is obtained by reading thecorresponding gage and the weight per unit of width for each wheel isobtained by the obvious method of dividing the weight by the width ofthe tire in inches;

By the use of two of the Weighting units, as indicated in Fig. 4, thesaine or nearly the same figures maybe lobtained in separate operationsat the front and rear and similarly treated, z'. e., the indicatedweights on any lcorresponding wheel divided by the tire width. A.. I

Otherwise a single weighing unit may be used. and the bearing pressureper `unit of width for each tire obtained by jacking the wheels in turnand figuring the weight borne by each wheel according to a well knownformula, that is, the distance from the point of weighing to the centerof the opposite tread being (a), the. distance between the centers oftreads being (b), thewei ht indicatedby the weighing unit being y), andlo/'tlle weight on the wheel lifted being t en a e Thevalues of (a), (b)and (y) being known, the value of can obviously be obtained. This isthen divided by the tire width. The

total weight may 'obviously be1determined` The desired number'ofweighing units as' offending vehicle is stopped, the lifting unitsdetermined by the authorities Vbeing carried in the trafiic oiicersmachine, when a vehicle isencountered which is under suspicion asexerting a bearing power on the tires greater than that allowed by theregulations, the

areplaced under it as already described, and the machine is liftedeither as a whole or by the front and rear separately, or as to eachwheel as already indicated, the data as to bearing thrust or weight perunit of width of the tires beingvthus immediately acces` sible to the4oflicer who is thus enabled to make the arrest or record the offensefor further adjudication, having the necessary evidence, or release thevehicle acquitted of suspicion as the case may be.

l have thus described a weighing device embodying my inventionspecifically and in detail in order that its nature and operation may beclearly understood; however, the specific terms herein are useddescriptively rather than in a limiting sense, the scope of theinvention being defined in the claims.

l/Vhat I claim and desire to secure by Letters Patent is:

1. A weighing device .for obtaining the bearing pressure on vehicletires consisting of a cylinder and piston with means for indicating theuid pressure in the cylinder, a jack, means for applying the weightlifted by the jack to thecylinder and piston to contract the pistonspace, said means including a shank, a weight supporting member for the,jack having a screw-threaded engagement with said shank, the axis of thescrew being parallel to the path of the piston, ratchet means forturning `the screw, and means for preventing relative rotation of thepiston and cylinder.

2. A method of determining the pressure of a road vehicle wheel on theroad surface, which consists in supporting the axle at two pointsbetween the wheels and equally spaced Vfrom the center of the axle, andmeasuring the supporting force adjacent the '-wheel the bearing pressureof which is.

to bedetermined.

Signed by me at Baltimore, Maryland, this 5th day of August, 1919. 1 iFREDERICK J. TROLL.

Witnesses:` I

EMMA AHLsLEcER, PORTER H. FLAUTT.

